Zinc negative electrode material with high-toughness, high-electrochemical-activity zinc sulfide protective layer and preparation method thereof

Abstract

The application discloses a zinc negative electrode material with a high-toughness and high-electrochemical-activity zinc sulfide protective layer and a preparation method thereof. The zinc negative electrode material is composed of a zinc metal matrix and a zinc sulfide protective layer. The zinc metal matrix is cold-rolled for multiple times. Then, a H2S-Ar mixed gas atmosphere laser-assisted synthesis technology is used to generate the zinc sulfide protective layer in situ on the cold-rolled zinc matrix. A zinc sulfide layer with a grain size of 20-150 nm, a (111) texture intensity higher than 3.0 and a layer thickness of 0.8-1.5 microns is prepared. The nanoindentation hardness of the zinc sulfide layer is greater than 6.0 GPa, and the electrochemical reaction activation energy is lower than 32.0 kJ / mol. The zinc negative electrode material with the zinc sulfide protective layer is obtained. In the aqueous zinc ion battery system, the zinc negative electrode material exhibits a cycle service life of more than 1700 h under a high current density of 10 mA / cm 2 . The application significantly improves the electrochemical reversibility and cycle stability of the zinc negative electrode, and the preparation process is highly controllable.

Description

Technical Field

[0001] This invention belongs to the field of zinc-ion battery technology, and particularly relates to a zinc anode material with a high-strength, high-toughness, and high-electrochemical-activity zinc sulfide protective layer and its preparation method. Background Technology

[0002] Developing low-cost, safe, environmentally friendly, and high-energy-density aqueous zinc-ion battery technology is a key measure to drive the rapid green and low-carbon transformation of energy. However, the uncontrollable dendrite growth of the zinc anode severely limits its large-scale application: irregular dendrites generate local high-stress zones during deposition, easily piercing the separator and contacting the positive electrode, causing a short circuit; simultaneously, the continuous hydrogen evolution and corrosion side reactions at the dendrite / electrolyte interface lead to irreversible consumption of active materials, resulting in rapid decay of coulombic efficiency. To overcome these bottlenecks, constructing an artificial protective layer on the surface of the metal anode has become a core strategy. This strategy aims to resist the high stress at the dendrite tips and induce planarization deposition by providing strong mechanical support; in addition, this protective layer can also reshape the electric field distribution at the electrode / electrolyte interface, guide uniform ion diffusion / nucleation, and suppress side reactions. Therefore, developing a more efficient artificial protective layer has significant strategic value for realizing the large-scale industrialization of zinc battery energy storage.

[0003] As can be seen from the above, an ideal artificial protective layer should possess both good electrochemical activity and mechanical strength. Zinc sulfide in the zinc sphalerite phase can meet these requirements due to the high electronegativity of sulfur. However, zinc sulfide protective layers prepared by conventional physical coating / high-temperature vapor phase method have excessively large grain sizes (>1 μm), resulting in a severe shortage of highly active grain boundaries; at the same time, they exhibit polycrystalline structural characteristics, forcing a large number of inactive (111) crystal planes to be exposed at the electrode / electrolyte interface; the above factors together limit its mechanical properties and electrochemical activity, thereby reducing the cycle life of the battery. Therefore, it is of great significance to synergistically achieve grain nano-sizing and (111) texture reinforcement of zinc sulfide protective layers and develop zinc anode materials with high strength, toughness, and high electrochemical activity. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide a zinc anode material with a high-strength, high-toughness, and high-electrochemical-activity zinc sulfide protective layer and its preparation method. Through H2S-Ar mixed atmosphere laser-assisted synthesis technology, a zinc sulfide protective layer with nanoscale grain size (20~150 nm) and strong (111) texture is generated in situ on the surface of a cold-rolled zinc metal substrate. This zinc sulfide protective layer, by introducing a sufficient amount of highly active grain boundaries and optimizing the (111) orientation ratio, simultaneously achieves high strength and toughness mechanical properties and excellent electrochemical reactivity, effectively suppressing dendrite growth and side reactions during cycling, thereby exhibiting an ultra-long cycle service life.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: The zinc anode material with a high-strength, high-toughness, and high-electrochemical-activity zinc sulfide protective layer has a cold-rolled strain of more than 70% in the zinc metal matrix and a thickness of 100 μm; the (111) texture strength of the zinc sulfide protective layer is higher than 3.0, the grain size is 20~150 nm, and the layer thickness is 0.8~1.5 μm; the nano-indentation hardness of the zinc sulfide protective layer is greater than 6.0 GPa, and the electrochemical reaction activation energy is lower than 32.0 kJ / mol.

[0006] The zinc anode material is at 10 mA / cm 2 It exhibits a cycle service life of over 1700 hours at current densities.

[0007] This invention provides a method for preparing a zinc anode material with a high-strength, high-toughness, and highly electrochemically active zinc sulfide protective layer, comprising the following steps: 1) Using low-temperature cold rolling technology, zinc sheets with a purity >99.9% are cold rolled to a reduction rate of 70%~90% and used as zinc metal matrix; 2) Fix the zinc metal substrate to the heating table, and adjust the distance between the zinc sulfide target and the substrate to 5~12 cm; pre-evacuate the gas pressure in the reaction chamber to 4×10 -8 The process involves introducing a Torr gas mixture followed by the introduction of H2S-Ar gas, while simultaneously raising the heating stage to 150-280°C. A KrF2 excimer laser is then activated, outputting laser light at a constant voltage of 24-26 kV and a pulse frequency of 2-5 Hz. The pulsed laser, focused by a lens, etches the zinc sulfide target, transforming it from a solid phase to a plasma state. Subsequently, a solid film is formed on the zinc metal substrate, creating a zinc sulfide protective layer. The deposition time is controlled to be 40-360 min. After deposition, a H2S-Ar gas mixture is continuously introduced into the reaction chamber, and the mixture is kept in situ at the set temperature for 30-120 min before being cooled to room temperature, thus obtaining a zinc anode material with a high-strength, high-toughness, and highly electrochemically active zinc sulfide protective layer.

[0008] Preferably, the distance between the zinc sulfide target and the zinc metal substrate is adjusted to 5~12 cm to ensure the uniformity of the deposited film and to control the grain size and crystal texture intensity of the deposited layer.

[0009] Preferably, during deposition, an H2S-Ar mixed gas is introduced until the pressure reaches 1.5 × 10⁻⁶. -1 ~3×10 -3 Torr, in which the volume ratio of H2S to Ar in the H2S-Ar mixture is controlled at 1:19 to 1:9. H2S can dynamically compensate for sulfur volatilization during the deposition process to suppress sulfur vacancies, while Ar can alleviate thermal damage to ensure dense film formation.

[0010] Preferably, after deposition, H2S-Ar mixed gas is continuously introduced until the gas pressure in the reaction chamber reaches 1~20 Torr, to ensure that a sulfur-rich environment is constructed during the cooling stage to suppress the formation of sulfur vacancies, while the gas pressure range is used to alleviate thermal stress and regulate grain growth.

[0011] The beneficial effects of this invention are: In an aqueous zinc-ion battery system, the zinc anode material prepared by this invention achieves a speed of 10 mA / cm². 2 It exhibits a cycle life exceeding 1700 h under high current density. The preparation method employs H2S-Ar mixed atmosphere laser-assisted synthesis technology to construct a zinc sulfide protective layer with high strength, toughness, and high electrochemical activity in situ on the surface of cold-rolled zinc metal anode, and obtain zinc anode material with this zinc sulfide protective layer. The nanoscale grains (20~150 nm) of the zinc sulfide protective layer provide a large number of highly active grain boundaries, effectively reducing the activation energy of zinc deposition reaction (<32.0 kJ / mol), improving ion diffusion rate and nucleation uniformity, and inducing efficient and ordered metal deposition; the increase in the number of grain boundaries promotes dislocation pile-up, thereby strengthening the interface layer (hardness greater than 6.0 GPa). In addition, the strong (111) texture (texture intensity greater than 3.0) ensures that the strong electronegativity (111) plane participates in the zinc deposition process as the main crystal plane, which can optimize the ion adsorption and diffusion process, while providing strong mechanical support. The aforementioned microstructural features simultaneously achieve both high strength and toughness mechanical properties and excellent electrochemical reactivity in the zinc sulfide protective layer, effectively inhibiting zinc dendrite growth and improving battery cycle life. This invention is used to improve the cycle life of zinc-ion batteries, with a highly controllable manufacturing process, providing a key solution for improving the cycle life and reliability of commercial zinc-ion batteries. Attached Figure Description

[0012] Figure 1 In the figures a and b, respectively, are scanning electron microscope images of the zinc anode materials Zn@ZnS_20 and Zn@ZnS_150 with high strength, high toughness, and high electrochemical activity zinc sulfide protective layer in the embodiments of the present invention; Figure 2 The X-ray diffraction (XRD) pattern of the zinc anode material Zn@ZnS_20 with a high-strength, high-toughness, and high-electrochemical-activity zinc sulfide protective layer in the embodiments of the present invention is shown. Figure 3 This is a nanoindentation hardness diagram of the zinc anode material Zn@ZnS_20 with a high-strength, high-toughness, and high-electrochemically active zinc sulfide protective layer in an embodiment of the present invention. Figure 4 This is a reaction activation energy diagram of cold-rolled zinc metal anode (Bare Zn) and zinc anode material Zn@ZnS_20 with a high-strength, high-toughness, and high-electrochemically active zinc sulfide protective layer in the embodiments of the present invention; Figure 5This is a cycle performance diagram of cold-rolled zinc metal anode (Bare Zn) and zinc anode material Zn@ZnS_20 with a high-strength, high-toughness, and high-electrochemically active zinc sulfide protective layer in the embodiments of the present invention; Detailed Implementation The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions herein are used to explain the invention but are not intended to limit it. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0013] This invention relates to a zinc anode material with a high-strength, high-toughness, and high-electrochemical-activity zinc sulfide protective layer and its preparation method. The zinc anode material consists of a zinc metal substrate and a zinc sulfide protective layer. The zinc metal substrate is cold-rolled multiple times to achieve a reduction rate of more than 70%. Subsequently, a zinc sulfide protective layer is generated in situ on the cold-rolled zinc substrate using H2S-Ar mixed atmosphere laser-assisted synthesis technology. During the process, the volume ratio of H2S-Ar mixed gas is specified, and the target-substrate spacing, deposition temperature, reaction time, and laser voltage are controlled to prepare a zinc sulfide layer with a grain size of 20~150 nm, a texture strength of (111) higher than 3.0, and a layer thickness of 0.8~1.5 μm. The nano-indentation hardness of the zinc sulfide layer is greater than 6.0 GPa, and the electrochemical reaction activation energy is lower than 32.0 kJ / mol. The zinc anode material with this layer is obtained. In an aqueous zinc-ion battery system, the zinc anode material prepared by this invention achieves a performance of 10 mA / cm 2 It exhibits a cycle service life of over 1700 hours at high current densities.

[0014] Example 1 Zinc sheets were repeatedly cold-rolled at low temperatures until a reduction rate of 90% was achieved, resulting in a zinc metal matrix. This matrix was then fixed on a heating table, and the distance between the zinc sulfide target and the zinc metal matrix was adjusted to 12 cm. The gas pressure in the reaction chamber was then evacuated to 4 × 10⁻⁶. -8 Torr, a 1:19 H2S-Ar mixture was introduced until the internal pressure reached 1.5 × 10⁻⁶. -1Torr, and at the same time, the heating stage is raised to 150°C; the KrF2 excimer laser with a wavelength of 248 nm is started, and the laser is output at a constant voltage of 24 kV and a pulse frequency of 5 Hz. After the pulse laser is focused by the lens, it etches the zinc sulfide target material to make it change from solid phase to plasma state. Then, it is transformed into a solid phase film on the surface of zinc metal substrate to form a zinc sulfide protective layer. The deposition time is controlled to be 40 min. After the deposition is completed, H2S-Ar mixed gas with a volume ratio of 1:19 is continuously introduced until the cavity gas pressure reaches 1.0 Torr. Then, it is kept at 150°C for 30 min and then cooled to room temperature to obtain a zinc anode material (Zn@ZnS_20) with a high strength and toughness and a high electrochemical activity zinc sulfide protective layer (average grain size of 20 nm, (111) texture strength of 3.2).

[0015] Example 2 Zinc sheets were repeatedly cold-rolled at low temperatures until a reduction rate of 80% was achieved, resulting in a zinc metal matrix. This matrix was then fixed on a heating table, and the distance between the zinc sulfide target and the zinc metal matrix was adjusted to 10 cm. The gas pressure in the reaction chamber was then evacuated to 4 × 10⁻⁶. -8 Torr, a 1:15 volume ratio H2S-Ar mixture is introduced until the internal pressure reaches 5 × 10⁻⁶. -2 Torr, and at the same time, the heating stage is raised to 200℃; the KrF2 excimer laser with a wavelength of 248nm is started, and the laser is output at a constant voltage of 25 kV and a pulse frequency of 4 Hz. After the pulse laser is focused by the lens, it etches the zinc sulfide target material to make it change from solid phase to plasma state. Then, it is transformed into a solid phase film on the surface of zinc metal substrate to form a zinc sulfide protective layer. The deposition time is controlled to be 120 min. After the deposition is completed, H2S-Ar mixed gas with a volume ratio of 1:15 is continuously introduced until the cavity gas pressure reaches 5.0 Torr. Then, it is kept at 200℃ for 60 min and then cooled to room temperature to obtain a zinc anode material (Zn@ZnS_40) with a high strength and toughness and a high electrochemical activity zinc sulfide protective layer (average grain size of 40 nm, (111) texture strength of 3.4).

[0016] Example 3 Zinc sheets were repeatedly cold-rolled at low temperatures until a reduction rate of 80% was achieved, resulting in a zinc metal matrix. This matrix was then fixed on a heating table, and the distance between the zinc sulfide target and the zinc metal matrix was adjusted to 8 cm. The gas pressure in the reaction chamber was then evacuated to 4 × 10⁻⁶. -8 Torr, then a 1:12 H2S-Ar mixture was introduced until the pressure inside the chamber reached 1×10⁻⁶. -2Torr, and at the same time, the heating stage is raised to 250°C; the KrF2 excimer laser with a wavelength of 248 nm is started, and the laser is output at a constant voltage of 26 kV and a pulse frequency of 3 Hz. After the pulse laser is focused by the lens, it etches the zinc sulfide target material to make it change from solid phase to plasma state. Then, it is transformed into a solid phase film on the surface of zinc metal substrate to form a zinc sulfide protective layer. The deposition time is controlled to be 220 min. After the deposition is completed, H2S-Ar mixed gas with a volume ratio of 1:12 is continuously introduced until the cavity gas pressure reaches 10.0 Torr. Then, it is kept at 250°C for 120 min and then cooled to room temperature to obtain a zinc anode material (Zn@ZnS_90) with a high strength and toughness and a high electrochemical activity zinc sulfide protective layer (average grain size of 90 nm, (111) texture strength of 3.4).

[0017] Example 4 Zinc sheets were repeatedly cold-rolled at low temperatures until a reduction rate of 70% was achieved, resulting in a zinc metal matrix. This matrix was then fixed on a heating table, and the distance between the zinc sulfide target and the zinc metal matrix was adjusted to 5 cm. The gas pressure in the reaction chamber was then evacuated to 4 × 10⁻⁶. -8 Torr, then a 1:9 H2S-Ar mixture was introduced until the pressure inside the chamber reached 3 × 10⁻⁶. -3 Torr, while heating the stage to 280°C; start the KrF2 excimer laser with a wavelength of 248 nm, output laser at a constant voltage of 26 kV and a pulse frequency of 2 Hz, the pulsed laser is focused by the lens and etches the zinc sulfide target material to make it change from solid phase to plasma state, and then it is transformed into a solid phase film on the surface of zinc metal substrate to form a zinc sulfide protective layer, and the deposition time is controlled to be 280 min; after the deposition is completed, the volume ratio is continuously introduced to reach 20.0 Torr, and then it is kept at 280°C for 120 min and then cooled to room temperature, thus obtaining a zinc anode material (Zn@ZnS_150) with a high strength and toughness and a high electrochemical activity zinc sulfide protective layer (average grain size of 150 nm, (111) texture strength of 3.6).

[0018] like Figure 1 In Figures a and b, the scanning electron microscope (SEM) images of zinc anode materials Zn@ZnS_20 and Zn@ZnS_150, respectively, which have high strength, high toughness, and high electrochemical activity zinc sulfide protective layers. Highly dense ZnS nanocrystal distributions were observed in the Zn@ZnS_20 and Zn@ZnS_150 samples. The Zn@ZnS_20 sample exhibited extremely small nanocrystals with an average grain size of 20 nm and uniform grain size. The Zn@ZnS_150 sample, on the other hand, exhibited relatively large nanocrystals with an average grain size of 150 nm and uniform grain size.

[0019] like Figure 2The XRD pattern of the zinc anode material Zn@ZnS_20 with a high-strength, high-toughness, and high-electrochemical-activity zinc sulfide protective layer shows that Zn@ZnS_20 has an extremely strong (111) diffraction peak intensity, and no other diffraction peaks of zinc sulfide were observed. This confirms that the zinc sulfide protective layer constructed in Example 1 has a strong (111) texture feature, and the (111) texture intensity is 3.2.

[0020] like Figure 3 The nanoindentation hardness diagram of Zn@ZnS_20, a zinc anode material with a high-strength, high-toughness, and high-electrochemical-activity zinc sulfide protective layer, shows that Zn@ZnS_20 exhibits extremely high hardness (~8 GPa). This is due to the mechanical strengthening caused by dislocation pile-up induced by a large number of grain boundaries and the preferred orientation of (111). This phenomenon indicates that the zinc sulfide protective layer can provide strong mechanical support to resist the high stress at the dendrite tip and induce planarization deposition.

[0021] like Figure 4 The activation energy diagram of the reaction of Zn@ZnS_20, a zinc anode material with a high-strength, high-toughness, and high-electrochemical-activity zinc sulfide protective layer, corresponding to the cold-rolled zinc metal anode, shows that the activation energy of Zn@ZnS_20 is significantly reduced compared to the cold-rolled bare zinc anode, indicating that the zinc sulfide protective layer can effectively reduce the diffusion and nucleation barrier of zinc ions.

[0022] Cold-rolled zinc metal anode (Bare Zn) and zinc anode material (Zn@ZnS_20) with a high-strength, high-toughness, and high-electrochemical-activity zinc sulfide protective layer were cut into 12 mm diameter circular electrodes as anodes. A 2M ZnSO4 aqueous solution was used as the electrolyte and glass fiber was used as the separator to assemble a symmetrical battery for cycle stability testing.

[0023] like Figure 5 The cycling performance diagram of the corresponding cold-rolled zinc metal anode material (Zn@ZnS_20) with a high-strength, high-toughness, and highly electrochemically active zinc sulfide protective layer shows a high cycling performance of up to 10 mA / cm². 2 At the specified current density, the battery corresponding to the cold-rolled zinc metal anode could only cycle for 93 hours; in contrast, the battery corresponding to Zn@ZnS_20 exhibited a stable cycle life exceeding 1700 hours. These phenomena confirm that a zinc sulfide protective layer with high strength, toughness, and high electrochemical activity can significantly improve the cycle life of the zinc anode.

[0024] The embodiments described above are merely preferred embodiments of the present invention and do not constitute a limitation on the scope of protection of this technical solution. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this invention should be included within the scope of protection of this invention. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. A zinc anode material with a high-strength, high-toughness, and highly electrochemically active zinc sulfide protective layer, characterized in that: The zinc metal matrix has a cold rolling strain greater than 70% and a thickness of 100 μm; the (111) texture strength of the zinc sulfide protective layer is higher than 3.0, the grain size is 20~150 nm, and the layer thickness is 0.8~1.5 μm; the nano-indentation hardness of the zinc sulfide protective layer is greater than 6.0 GPa, and the electrochemical reaction activation energy is lower than 32.0 kJ / mol.

2. The zinc anode material with a high-strength, high-toughness, and highly electrochemically active zinc sulfide protective layer according to claim 1, characterized in that: The zinc anode material is at 10 mA / cm 2 It exhibits a cycle service life of over 1700 hours at current densities.

3. The method for preparing the zinc anode material with a high-strength, high-toughness, and highly electrochemically active zinc sulfide protective layer as described in claim 1 or 2, characterized in that, Includes the following steps: 1) Using low-temperature cold rolling technology, zinc sheets with a purity >99.9% are cold rolled to a reduction rate of 70%~90% and used as zinc metal matrix; 2) Fix the zinc metal substrate to the heating stage and adjust the distance between the zinc sulfide target and the zinc metal substrate; pre-pump the gas pressure in the reaction chamber to 4×10. -8 The process involves introducing a Torr gas mixture followed by the introduction of H2S-Ar gas, while simultaneously raising the heating stage to 150-280°C. A KrF2 excimer laser is then activated, outputting laser light at a constant voltage of 24-26 kV and a pulse frequency of 2-5 Hz. The pulsed laser, focused by a lens, etches the zinc sulfide target, transforming it from a solid phase to a plasma state. Subsequently, a solid film is formed on the zinc metal substrate, creating a zinc sulfide protective layer. The deposition time is controlled to be 40-360 min. After deposition, a H2S-Ar gas mixture is continuously introduced into the reaction chamber, and the mixture is kept in situ at the set temperature for 30-120 min before being cooled to room temperature, thus obtaining a zinc anode material with a high-strength, high-toughness, and highly electrochemically active zinc sulfide protective layer.

4. The preparation method according to claim 3, characterized in that: Adjust the distance between the zinc sulfide target and the zinc metal substrate to 5~12 cm.

5. The preparation method according to claim 3, characterized in that: During deposition, an H2S-Ar mixture was introduced until the pressure reached 1.5 × 10⁻⁶. -1 ~3×10 -3 Torr, in which the volume ratio of H2S to Ar in the H2S-Ar mixture is controlled at 1:19 to 1:

9.

6. The preparation method according to claim 3, characterized in that: After deposition, H2S-Ar mixed gas is continuously introduced until the gas pressure in the reaction chamber reaches 1~20 Torr.

Images